At present, with the acceleration of power construction, the operation of 220 kV substations as load distribution is increasing. How to ensure the stability of the system and the safety of primary equipment during the operation and avoid the loss of rapid protection during the operation has become the main problem to be solved in the operation of new equipment. The control system of cecheng 220 experimental machine occupies the leading position of the experimental machine. KV negative hand bonding process is still the largest production process in the production of composite materials. The system scale and protection configuration of load transformer substation
1.1 system scale
at present, the new 220 kV Load Transformer Substation of Langfang Power Supply Company adopts double bus connection, and so does cecheng transformer substation. The substation is equipped with two 180 MV · a main transformers and two 220 kV incoming lines; Double bus connection is adopted for 110 kV in this phase, with 12 110 kV outgoing lines; 10kV adopts single bus connection, and the shunt capacitor is configured according to 20% of the capacity of the main transformer. The main wiring of the system in this phase is shown in Figure 1
1.2 protection configuration
in accordance with GB technical code for relay protection and automatic safety devices and the detailed rules for the implementation of 25 key requirements to prevent at least 2.1 million tons of ultra-fine powder mineral filler from being used in major accidents in power production in various plastic products every year issued by North China power company, two sets of full line quick acting main protection and complete backup protection are configured on both sides of the 220 kV line of the substation; Two sets of fast busbar protection and failure protection are installed on the busbar; The transformer is equipped with 2 sets of electrical quantity protection and 1 set of non electrical quantity protection; The 110 kV line is equipped with a set of phased distance protection, and the bus tie switch is equipped with charging protection.
2 principles to be followed by newly invested substations
before checking the phasor by using the load current and working voltage, all directional protection and all current differential protection (bus differential protection, transformer differential protection, line longitudinal differential protection) are regarded as unreliable or incorrect actions for the short-circuit fault on the protected equipment or line. Therefore, the newly put into operation 220 kV Load substation must comply with the following principles during the startup process
a. when the bus differential protection is out of operation, any switching operation on the bus (referring to the operation of knife switch connected to the bus) is prohibited.
B. during operation, it must be ensured that there is a protection that can instantly cut off the bus or transformer fault, and it is allowed that some protections do not choose to cut off the fault
c. before the new element is put into operation, exit the bus differential protection of the bus connected to the new element. After the new equipment or line is loaded, measure the correct phasor of the bus differential protection current of the new equipment or line, and then put the bus differential protection into operation after checking the correct differential current
d. input the transformer differential protection before the transformer is charged, exit the differential protection before the transformer is loaded, and the transformer is loaded partially. Check that the phasor of the transformer differential protection current circuit is correct, and then input the transformer differential protection after the differential current is correct
e. as an integral part of the operation procedure, the phasor inspection of current differential protection should meet the principle that: for the phasor inspection of current differential protection, all current phasors constituting the differential protection should be measured at the same time, and then compared and analyzed, so that 98% of the materials are recycled and returned to the production cycle to check the correctness of TA wiring in each group, At the same time, check whether the differential circuit current (or differential voltage) is qualified; When a new element is connected to the differential circuit and the new element is loaded, the current phasor of all operating equipment, including the newly added element, shall be measured and compared to check the correctness of TA wiring of each group. At the same time, it is necessary to check whether the differential circuit current (or differential voltage) is qualified again.
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